Twelve men and two youths have been sentenced for "mob violence of an extreme nature" during last summer's riots, during which a police station was fire-bombed.

The group, which included two 16-year-olds, were sentenced at Nottingham Crown Court for the roles they played in city centre disturbances last year. Nine lighted petrol bombs were thrown at Canning Circus police station, the court heard.

Yesterday 10 of the men were sentenced for riot while four others were sentenced for violent disorder. Sentencing all 14, Judge Michael Stoke QC, Recorder of Nottingham, described their actions as "a calculated defiance of the criminal law and a deliberate attack on the police".

He added: "The numbers involved – far more numerous than those apprehended – must have caused real fear to decent citizens who witnesses these events or whose property sustained damage during the course of them."

The six-week trial heard witnesses describe the scene as a "war zone", seeing petrol bombs thrown at the police station during an "organised and planned attack".

The court heard that the gang had planned to meet armed with weapons, sticks and bottles filled with petrol, with the intent of setting the police station alight.

Lance Francis, 25, received the longest term of 14 years in jail after being convicted by a jury of riot, arson with intent to endanger life and attempting to pervert the course of justice.